Numerous industries have long sought to reduce the amount of labor necessary to join various work pieces by welding, while increasing the quality of the joints. In fact, automated welding systems have greatly improved weld quality while reducing costs in many industries. However, to date, very few automated welding systems have effectively dealt with weld joints having continuously variable characteristics.
The effects of weld joints with great variability is most commonly felt in industries that join large sections of material, such as the automobile, aviation, heavy manufacturing, and shipbuilding industries, among others. For example, in the shipbuilding industry, a major limitation on the productivity of a shipyard is the erection of the ship from units. Most shipyards have effective systems for welding longitudinal and transverse members to panels in production. These panels are then fitted into units, which are then welded together to create super-units. The cost of erection welding the units and super-units is often more than five times the cost of production welding the panels due in part to the extensive labor required for fit-up of the units. Generally the edges of one unit do not match directly with the edges of an adjoining unit. Fit-up issues most commonly arise due to distortions and the accumulation of fabrication tolerances causing variable gaps and mismatch along the weld seams.
Continuing with the shipbuilding example, erection welding is most commonly completed by manual flux-cored arc welding (FCAW), gas-metal arc welding (GMAW), or submerged arc-welding (SAW). Mechanized tractors are used as much as possible, especially on long weld seams. Generally each weld seam requires multiple weld passes with each pass adding a weld bead to the seam. Currently, systems are limited in the quality of the welds produced and in the amount of adverse fit-up conditions that may be overcome in trying to produce a uniform groove fill. In fact, most shipyards still use tractor systems that require the operator to closely follow the tractor and make physical adjustments, in an attempt to achieve a uniform fill.
More advanced robotic tractors have been developed to track weld seams and perform some degree of adaptive welding, yet they are generally too costly and heavy to employ in shipyard fabrication and provide little if any control on the quality of the welds produced. For instance, laser-guided welding robots have been developed for erection welding, but such systems typically cost over $150,000 and require significant operator training and programming. Such systems are only justified on the most critical weldments, particularly where 100% UT volumetric inspection is required.
Prior adaptive welding methods have lacked the ability to ensure weld quality in part because they generally focus on only varying one of the wire feed speed, the voltage, or the travel speed of the welding tractor. Weld quality cannot be assured by varying only one of these variables. The present invention may systematically vary the voltage, the wire feed speed, and the travel speed along with a plurality of experimentally optimized welding parameters. The experimentally optimized welding parameters are developed from experimentally determined process relationships developed to result in a predetermined base metal dilution and weld bead shape. By ensuring that the adaptive welding method results in base metal dilution in a predetermined range, an increased level of weld quality is obtained.
Additionally, prior art systems have lacked the ability to allow a user to easily change numerous complex welding parameters at the same time, with a single input to influence the weld bead size, while maintaining the weld quality during the welding process. The present invention utilizes the concept of changing a single synergic fill number to thereby influence a plurality of optimized parameters, to not only maximize the use of optimized welding parameters but to also avoid the manual, individual adjustments, of a multitude of complex welding parameters by the user to vary the size of the weld bead.
Accordingly, the art has needed a means for providing a durable, cost effective automated adaptive and synergic fill welding system that offers robust seam tracking, weld quality control, and production optimization. While some of the prior art devices attempted to improve the state of the art, none have achieved the benefits of the present invention. Additionally, the prior art has generally not provided the level of quality control available from the present invention. Further, the prior art has failed to achieve the unique and novel configurations and capabilities of the present invention. With these capabilities taken into consideration, the instant invention addresses many of the shortcomings of the prior art and offers significant benefits heretofore unavailable. Lastly, none of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.